When I tried to boot into my new ZFS root, the boot went fine up until it was going to mount the root filesystem.
It just stuck on “trying to mount root from zfs:twotb/root” and then absolutely nothing happend. I left it for 10-15 minutes but nothing, no error message or anything. I tried a zillion things and googled like mad, but I only found one similar problem. That guy didn’t find the root cause though, but claimed he fiddled some with fstab and then it started to work. That did’nt help me.
I extracted a new installation and that booted fine from the same ZFS pool, so I knew the problem wasn’t with the pool. I then tried replacing the boot-folder and the etc-folder, but the old install still wouldn’t boot.
So I started comparing the differences in files and folders and then it hit me.
I HAD NO DEV FOLDER! Since I excluded that in my rsync. So I created an empty dev-folder in the old root, made it 555 and rebooted. And what do you know, it booted fine after that!